1. Field of the Invention
This invention relates to a fermentation-promoting substance capable of activating yeast for use in the production of fermented products, accelerating the rate of fermentation, and shortening the period of fermentation. More specifically, it relates to a fermentation-promoting substance derived from a residue such as spent grains and trub, that contains the grain shells of cereals in use obtained during the production of fermented liquor, like beer, which employ the cereals, as well as to a method for preparation of the fermentation-promoting substance, a method for the production of a fermented product using the same, and a method for restoring the activity of a yeast using the same.
2. Related Background Art
For example, in the publication of Japanese Patent Unexamined Appln. Hei 9-94085 by the present applicant, there is disclosed that spent grains (beer dregs) are added to the fermentation steps of beer production or the like so that the fermentation can be promoted.
The same publication also discloses that the supernatant (or extract) obtained by treating spent grains with lactic acid is used in place of the spent grains themselves. This is because there are a lot of unwanted materials in spent grains that do not contribute to the promotion of fermentation and a large quantity of spent grains is needed to be put in when the spent grains are to be added directly.
However, when this extract is used, it is possible that the fermentation-promoting ingredients are immidiately taken up by a yeast and thus the yeast will be activated at once to cause the beer quality, such as flavor, to change. In addition, the preservation and handling of such an extract is not easy. Thus, its utilization has never been satisfactory.
This invention is intended for solving the above-stated problems and enables the time of fermentation to be shortened by activating yeast consistently in a time-dependent manner and by accelerating the rate of fermentation while adequately preventing the transient, sudden progression of the fermentation. Furthermore, it aims at providing a fermentation-promoting substance that is easy to preserve and handle, as well as a method for its preparation.
In addition, the invention aims at providing a method that allows a fermented product to be produced stably for a short period of time, as well as a method capable of restoring the activity of a yeast consistently.
In an effort to solve the above-stated problems, the present inventors repeated thorough investigations. Consequently, the following have been discovered: if a residue such as spent grains, which has been obtained from the process of the production of fermented liquor, is treated with acid to yield supernatant and the supernatant is further subjected to neutralization treatment, then a substance contributable to the promotion of fermentation can selectively be extracted in the form of insoluble salts from the residue; and at the same time, it is possible to effectively remove unwanted substances such as proteins and lipids that are not connected with but rather have an impediment effect on the promotion of fermentation. It has further been discovered that the above-stated objectives are attained by using the thus-obtained solid fermentation-promoting substance. This invention has been accomplished based on this finding.
The method for preparing a solid fermentation-promoting substance according to this invention comprises the steps of:
subjecting a residue obtainable from a process of production of a fermented liquor to acid treatment (preferably in the range of pH 3-4) and separating supernatant from the acid treatment to obtain a liquid fermentation-promoting substance; and
subjecting the resulting liquid fermentation-promoting substance to neutralization treatment (preferably in the range of pH 6-8) to obtain the solid fermentation-promoting substance.
Preferably, the method for preparing a solid fermentation-promoting substance according to the invention as described above further comprises the step of removing at least part of protein and lipid contained in the residue and/or the step of drying the solid fermentation-promoting substance.
The solid fermentation-promoting substance of the invention is a product obtained by the method comprising the steps of:
subjecting a residue obtainable from a process of production of a fermented liquor to acid treatment (preferably in the range of pH 3-4) and separating supernatant from the acid treatment to obtain a liquid fermentation-promoting substance; and
subjecting the resulting liquid fermentation-promoting substance to neutralization treatment (preferably in the range of pH 6-8) to obtain the solid fermentation-promoting substance.
Preferably, the solid fermentation-promoting substance of the invention is a product obtained by the method comprising, in addition to the steps as described above, the step of removing at least part of protein and lipid contained in the residue and/or the step of drying the solid fermentation-promoting substance.
The method for producing a fermented product according to the invention comprises the step of fermenting by yeast, an object to be fermented in the presence of the solid fermentation-promoting substance to obtain the fermented product.
Following the method for producing a fermented product according to the invention as described above, in the fermentation step the solid fermentation-promoting substance may be added to the object to be fermented containing a yeast, or alternatively, a yeast to which the solid fermentation-promoting substance has been added in advance may be added to the object to be fermented.
The method for restoring the activity of a yeast according to the invention comprises the step of adding to the yeast, the solid fermentation-promoting substance of the invention.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.